Substrate processing apparatus and substrate processing method

ABSTRACT

A substrate processing apparatus configured to process a substrate includes a substrate holder configured to hold, in a combined substrate in which a front surface of a first substrate and a front surface of a second substrate are bonded to each other, the second substrate; a periphery modification unit configured to form a peripheral modification layer by radiating laser light for periphery to an inside of the first substrate held by the substrate holder along a boundary between a peripheral portion of the first substrate as a removing target and a central portion thereof; and an internal modification unit configured to form, after the peripheral modification layer is formed by the periphery modification unit, an internal modification layer by radiating laser light for internal surface to the inside of the first substrate held by the substrate holder along a plane direction of the first substrate.

TECHNICAL FIELD

The various aspects and embodiments described herein pertain generallyto a substrate processing apparatus and a substrate processing method.

BACKGROUND

Patent Document 1 discloses a manufacturing method for a stackedsemiconductor device. In this manufacturing method, the stackedsemiconductor device is produced by stacking two or more semiconductorwafers. At this time, after each semiconductor wafer is stacked onanother semiconductor wafer, a rear surface of the semiconductor waferis ground so that it has a required thickness.

It is described in Patent Document 2 that a circular plate-shapedgrinding tool having abrasive grains at a peripheral portion thereof isrotated and at least an outer peripheral surface of the grinding tool isbrought into linear contact with a semiconductor wafer to grind acircumferential end of the semiconductor wafer into a substantiallyL-shape. The semiconductor wafer is produced by bonding two sheets ofsilicon wafers.

PRIOR ART DOCUMENT

Patent Document 1: Japanese Patent Laid-open Publication No. 2012-069736

Patent Document 2: Japanese Patent Laid-open Publication No. H09-216152

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

Exemplary embodiments provide a technique capable of efficientlyperforming, in a combined substrate in which substrates are bonded toeach other, pre-treatments for removing of a peripheral portion of asingle substrate and thinning of this single substrate.

Means for Solving the Problems

In an exemplary embodiment, a substrate processing apparatus configuredto process a substrate includes a substrate holder configured to hold,in a combined substrate in which a front surface of a first substrateand a front surface of a second substrate are bonded to each other, thesecond substrate; a periphery modification unit configured to form aperipheral modification layer by radiating laser light for periphery toan inside of the first substrate held by the substrate holder along aboundary between a peripheral portion of the first substrate as aremoving target and a central portion thereof; and an internalmodification unit configured to form, after the peripheral modificationlayer is formed by the periphery modification unit, an internalmodification layer by radiating laser light for internal surface to theinside of the first substrate held by the substrate holder along a planedirection of the first substrate.

Effect of the Invention

According to the exemplary embodiments, it is possible to efficientlyperform, in the combined substrate in which the substrates are bonded toeach other, the pre-treatments for removing of the peripheral portion ofthe single substrate and thinning of this single substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view illustrating a configuration of a wafer processingsystem according to an exemplary embodiment.

FIG. 2 is a side view illustrating a schematic structure of a combinedwafer.

FIG. 3 is a side view illustrating a schematic structure of a part ofthe combined wafer.

FIG. 4 is a plan view illustrating a schematic configuration of amodifying apparatus.

FIG. 5 is a side view illustrating the schematic configuration of themodifying apparatus.

FIG. 6 is a plan view illustrating a schematic configuration of aperiphery removing apparatus.

FIG. 7 is a side view illustrating the schematic configuration of theperiphery removing apparatus.

FIG. 8 is a longitudinal cross sectional view illustrating a schematicconfiguration of a transfer arm.

FIG. 9 is a flowchart illustrating main processes of a wafer processingaccording to a first exemplary embodiment.

FIG. 10A to FIG. 10F are explanatory diagrams illustrating the mainprocesses of the wafer processing according to the first exemplaryembodiment.

FIG. 11A to FIG. 11E are explanatory diagrams illustrating mainprocesses of a modifying processing.

FIG. 12 is an explanatory diagram showing a state in which a peripheralmodification layer is being formed in a processing target wafer.

FIG. 13 is an explanatory diagram showing a state in which theperipheral modification layer is formed in the processing target wafer.

FIG. 14 is an explanatory diagram showing a state in which a splitmodification layer is being formed in the processing target wafer.

FIG. 15 is an explanatory diagram showing a state in which the splitmodification layer is formed in the processing target wafer.

FIG. 16 is an explanatory diagram showing a state in which an internalmodification layer is being formed in the processing target wafer.

FIG. 17 is an explanatory diagram showing a state in which the internalmodification layer is formed in the processing target wafer.

FIG. 18 is an explanatory diagram showing a state in which a peripheralportion is being removed.

FIG. 19A and FIG. 19B are explanatory diagrams showing a state in whicha rear surface wafer is being separated from the processing targetwafer.

FIG. 20 is a side view illustrating a schematic configuration of aperiphery removing apparatus according to another exemplary embodiment.

FIG. 21 is a plan view illustrating a schematic configuration of amodifying apparatus according to another exemplary embodiment.

FIG. 22 is a plan view illustrating a schematic configuration of amodifying apparatus according to still another exemplary embodiment.

FIG. 23A and FIG. 23B are explanatory diagrams illustrating mainprocesses of a wafer processing according to a modification example ofthe first exemplary embodiment.

FIG. 24 is a flowchart illustrating main processes of a wafer processingaccording to a second exemplary embodiment.

FIG. 25A to FIG. 25E are explanatory diagrams illustrating the mainprocesses of the wafer processing according to the second exemplaryembodiment.

FIG. 26A and FIG. 26B are explanatory diagrams illustrating a state inwhich a rear surface wafer is being separated from a processing targetwafer in the second exemplary embodiment.

FIG. 27 is a side view illustrating a schematic configuration of aremoving/separating apparatus.

FIG. 28 is a flowchart illustrating main processes of a wafer processingaccording to a third exemplary embodiment.

FIG. 29A to FIG. 29F are explanatory diagrams illustrating the mainprocesses of the wafer processing according to the third exemplaryembodiment.

FIG. 30 is a longitudinal cross sectional view illustrating a schematicconfiguration of a transfer arm according to another exemplaryembodiment.

FIG. 31 is a longitudinal cross sectional view illustrating a schematicconfiguration of a peripheral portion of an attraction plate accordingto the another exemplary embodiment.

FIG. 32A and FIG. 32B are explanatory diagrams illustrating a state inwhich a peripheral portion of a processing target wafer is being removedin the transfer arm according to the another exemplary embodiment.

FIG. 33 is a plan view illustrating a schematic configuration of amodifying apparatus according to another exemplary embodiment.

FIG. 34 is an explanatory diagram illustrating a state in which aperipheral modification layer is being formed in a processing targetwafer in the another exemplary embodiment.

FIG. 35 is an explanatory diagram illustrating a state in which aninternal modification layer is being formed in the processing targetwafer in the another exemplary embodiment.

DETAILED DESCRIPTION

In a manufacturing process for a semiconductor device, a semiconductorwafer having, for example, a plurality of devices such as electroniccircuits on a front surface thereof is thinned by grinding a rearsurface of the wafer, as described in Patent Document 1, for example.

The grinding of the rear surface of the wafer is performed by rotatingthe wafer and a grinding whetstone and lowering the grinding whetstonein a state that the grinding whetstone is in contact with the rearsurface of the wafer, for example. In this case, since the grindingwhetstone is worn away, it needs to be replaced regularly. Further,since grinding water is used in the grinding processing, disposal of awaste liquid is also required. As a result, a running cost is increasedin the conventional wafer thinning processing.

Typically, a peripheral portion of the wafer is chamfered. If, however,the grinding processing is performed on the rear surface of the wafer asstated above, the peripheral portion of the wafer is given a sharppointed shape (a so-called knife edge shape). If so, chipping takesplace at the peripheral portion of the wafer, and the wafer may bedamaged. Thus, there is performed a so-called edge trimming of removingthe peripheral portion of the wafer prior to the grinding processing.

The end surface grinding apparatus described in the aforementionedPatent Document 2 is an apparatus configured to perform this edgetrimming. In this end surface grinding apparatus, however, since theedge trimming is performed by the grinding, a whetstone is worn away andneeds to be replaced regularly. Further, since a large amount of thegrinding water is used, the disposal of the waste liquid is required.For these reasons, the running cost is increased in the conventionaledge trimming.

To carry out the thinning and the edge trimming efficiently, the presentdisclosure provides a technique capable of performing pre-treatmentstherefor efficiently. Hereinafter, a wafer processing system as asubstrate processing apparatus and a wafer processing method as asubstrate processing method according to an exemplary embodiment will bedescribed with reference to the accompanying drawings. Further, in thepresent specification and the drawings, parts having substantially samefunctional configurations will be assigned same reference numerals, andredundant description thereof will be omitted.

First, a configuration of the wafer processing system according to thepresent exemplary embodiment will be described. FIG. 1 is a plan viewillustrating a schematic configuration of a wafer processing system 1.

The wafer processing system 1 performs a required processing on acombined wafer T as a combined substrate in which a processing targetwafer W as a first substrate and a support wafer S as a second substrateare bonded to each other, as illustrated in FIG. 2 and FIG. 3. In thewafer processing system 1, a peripheral portion We of the processingtarget wafer W is removed, and the processing target wafer W is thinned.Hereinafter, in the processing target wafer W, a surface bonded to thesupport wafer S will be referred to as “front surface Wa,” and a surfaceopposite to the front surface Wa will be referred to as “rear surfaceWb.” Likewise, in the support wafer S, a surface bonded to theprocessing target wafer W will be referred to as “front surface Sa,” anda surface opposite to the front surface Sa will be referred to as “rearsurface Sb”.

The processing target wafer W is a semiconductor wafer such as, but notlimited to, a silicon wafer, and has, on the front surface Wa thereof, adevice layer (not shown) including a plurality of devices. Further, anoxide film F, for example, a SiO₂ film (TEOS film) is further formed onthe device layer. The peripheral portion We of the processing targetwafer W is chamfered, and a thickness of the peripheral portion Wedecreases toward a leading end thereof on a cross section thereof. Here,the peripheral portion We is a portion to be removed by edge trimmingand ranges from, e.g., 1 mm to 5 mm from an edge of the processingtarget wafer W in a diametrical direction thereof.

In FIG. 2, for the sake of simplicity of illustration, illustration ofthe oxide film F is omitted. In the other drawings recited in thefollowing description, illustration of the oxide film F may sometimes beomitted as well.

The support wafer S is a wafer configured to support the processingtarget wafer W, and is, for example, a silicon wafer. An oxide film (notshown) is formed on the surface Sa of the support wafer S. Further, thesupport wafer S serves as a protection member which protects the deviceson the front surface Wa of the processing target wafer W. Further, ifthe support wafer S has a plurality of devices on the front surface Sathereof, a device layer (not shown) is formed on the front surface Sa,the same as in the processing target wafer W.

Here, if the processing target wafer W and the support wafer S arebonded at the peripheral portion We of the processing target wafer W,the peripheral portion We may not be removed appropriately. For thereason, at an interface between the processing target wafer W and thesupport wafer S, a bonding region Aa where the oxide film F and thefront surface Sa of the support wafer S are bonded and a non-bondingregion Ab are formed. The non-bonding region Ab is located at an outsideof the bonding region Aa in the diametrical direction. Since thisnon-bonding region Ab is provided, the peripheral portion We can beappropriately removed. Further, it is desirable that an outer endportion of the bonding region Aa is located slightly outer than an innerend portion of the peripheral portion We to be removed in thediametrical direction, as will be described in detail.

As depicted in FIG. 1, the wafer processing system 1 includes acarry-in/out station 2 and a processing station 3 connected as one body.In the carry-in/out station 2, a cassette Ct capable of accommodatingtherein a multiple number of combined wafers T is carried to/from theoutside, for example. The processing station 3 is equipped with variouskinds of processing apparatuses configured to perform requiredprocessings on the combined wafers T.

A cassette placing table 10 is provided in the carry-in/out station 2.In the shown example, a plurality of, for example, three cassettes Ctcan be arranged on the cassette placing table 10 in a row in the Y-axisdirection. Further, the number of the cassettes Ct placed on thecassette placing table 10 is not limited to the example of the presentexemplary embodiment but can be selected as required.

In the carry-in/out station 2, a wafer transfer device 20 is providedadjacent to the cassette placing table 10 at a negative X-axis side ofthe cassette placing table 10. The wafer transfer device 20 isconfigured to be movable on a transfer path 21 which is elongated in theY-axis direction. Further, the wafer transfer device 20 is equippedwith, for example, two transfer arms 22 each of which is configured tohold and transfer the combined wafer T. Each transfer arm 22 isconfigured to be movable in a horizontal direction and a verticaldirection and pivotable around a horizontal axis and a vertical axis.Further, the configuration of the transfer arm 22 is not limited to theexemplary embodiment, and various other configurations may be adopted.The wafer transfer device 20 is configured to be capable of transferringthe combined wafer T to/from the cassette Ct of the cassette placingtable 10 and a transition device 30 to be described later.

In the carry-in/out station 2, the transition device 30 configured todeliver the combined wafer T is provided adjacent to the wafer transferdevice 20 at a negative X-axis side of the wafer transfer device 20.

The processing station 3 is provided with, for example, three processingblocks G1 to G3. The first processing block G1, the second processingblock G2 and the third processing block G3 are arranged side by side inthis sequence from a positive X-axis side (from a carry-in/out station 2side) toward a negative X-axis side.

The first processing block G1 is equipped with an etching apparatus 40,a cleaning apparatus 41 and a wafer transfer device 50. The etchingapparatus 40 and the cleaning apparatus 41 are stacked on top of eachother. Further, the number and the layout of the etching apparatus 40and the cleaning apparatus 41 are not limited to the shown example. Byway of example, the etching apparatus 40 and the cleaning apparatus 41may be elongated in the X-axis direction and arranged side by side whenviewed from the top. Further, a plurality of etching apparatuses 40 anda plurality of cleaning apparatuses 41 may be respectively stacked ontop of each other.

The etching apparatus 40 is configured to etch the rear surface Wb ofthe processing target wafer W grounded by a processing apparatus 80 tobe described later. By way of example, by supplying a chemical liquid(etching liquid) onto the rear surface Wb, the rear surface Wb iswet-etched. For instance, HF, HNO₃, H₃PO₄, TMAH, Choline, KOH, or thelike may be used.

The cleaning apparatus 41 is configured to clean the rear surface Wb ofthe processing target wafer W grounded by the processing apparatus 80 tobe described later. By way of example, by bringing a brush into contactwith the rear surface Wb, the rear surface Wb is cleaned by beingscrubbed. Furthermore, a pressurized cleaning liquid may be used for thecleaning of the rear surface Wb. In addition, the cleaning apparatus 41may be configured to clean the rear surface Sb of the support wafer S aswell as the rear surface Wb of the processing target wafer W.

The wafer transfer device 50 is disposed at, for example, a negativeY-axis side of the etching apparatus 40 and the cleaning apparatus 41.The wafer transfer device 50 has, for example, two transfer arms 51 eachof which is configured to hold and transfer the combined wafer T. Eachtransfer arm 51 is configured to be movable in a horizontal directionand a vertical direction and pivotable around a horizontal axis and avertical axis. Further, the configuration of the transfer arm 51 is notlimited to the exemplary embodiment, and various other configurationsmay be adopted. Additionally, the wafer transfer device 50 is configuredto be capable of transferring the combined wafer T to/from thetransition device 30, the etching apparatus 40, the cleaning apparatus41 and a modifying apparatus 60 to be described later.

The second processing block G2 is equipped with the modifying apparatus60, a periphery removing apparatus 61 and a wafer transfer device 70.The modifying apparatus 60 and the periphery removing apparatus 61 arestacked on top of each other. Further, the number and the layout of themodifying apparatus 60 and the periphery removing apparatus 61 is notlimited to the example of the present exemplary embodiment.

The modifying apparatus 60 is configured to form a peripheralmodification layer, a split modification layer and an internalmodification layer by radiating laser light to an inside of theprocessing target wafer W. A specific configuration of the modifyingapparatus 60 will be elaborated later.

The periphery removing apparatus 61 is configured to remove theperipheral portion We of the processing target wafer W, starting fromthe peripheral modification layer formed by the modifying apparatus 60.A specific configuration of the periphery removing apparatus 61 will beelaborated later.

The wafer transfer device 70 is disposed at, for example, a positiveY-axis side of the modifying apparatus 60 and the periphery removingapparatus 61. The wafer transfer device 70 is equipped with, forexample, two transfer arms 71 each of which is configured to hold andtransfer the combined wafer T. Each transfer arm 71 is supported at amulti-joint arm member 72 and configured to be movable in a horizontaldirection and a vertical direction and pivotable around a horizontalaxis and a vertical axis. A specific configuration of the transfer arm71 will be elaborated later. The wafer transfer device 70 is configuredto be capable of transferring the combined wafer T to/from the cleaningapparatus 41, the modifying apparatus 60, the periphery removingapparatus 61 and the processing apparatus 80 to be described later.

The third processing block G3 is equipped with the processing apparatus80. The number and the layout of the processing apparatus 80 is notlimited to the example of the present exemplary embodiment, and aplurality of processing apparatuses 80 may be arranged as required.

The processing apparatus 80 is configured to grind the rear surface Wbof the processing target wafer W. Further, the processing apparatus 80is configured to remove, in the rear surface Wb having the internalmodification layer formed therein, the corresponding internalmodification layer, and also removes the peripheral modification layer.To be specific, the processing apparatus 80 grinds the rear surface Wbby rotating the processing target wafer W and a grinding whetstone (notshown) in the state that the rear surface Wb of the processing targetwafer W held by the chuck 81 is in contact with the grinding whetstone.Further, in the present exemplary embodiment, the chuck 81 and thegrinding whetstone (not shown) constitute a processing unit. Further, acommonly known grinding apparatus (polishing apparatus) is used as theprocessing apparatus 80. For example, an apparatus described in JapanesePatent Laid-open Publication No. 2010-069601 may be used.

The above-described wafer processing system 1 is equipped with a controldevice 90. The control device 90 is implemented by, for example, acomputer, and includes a program storage (not shown). A program forcontrolling a processing of the combined wafer Tin the wafer processingsystem 1 is stored in the program storage. Further, the program storagealso stores therein a program for implementing a substrate processing tobe described later in the wafer processing system 1 by controlling theabove-described various processing apparatuses and a driving system suchas the transfer devices. Further, the programs may be recorded in acomputer-readable recording medium H, and may be installed from thisrecording medium H to the control device 90.

Now, the aforementioned modifying apparatus 60 will be described. FIG. 4is a plan view illustrating a schematic configuration of the modifyingapparatus 60. FIG. 5 is a side view illustrating the schematicconfiguration of the modifying apparatus 60.

The modifying apparatus 60 is equipped with a chuck 100 as a holderconfigured to hold the combined wafer Ton a top surface thereof. Thechuck 100 is configured to attract and hold the support wafer S in thestate that the processing target wafer W is placed at an upper side andthe support wafer S is placed at a lower side. The chuck 100 issupported on a slider table 102 with an air bearing 101 therebetween. Arotator 103 is provided at a bottom surface side of the slider table102. The rotator 103 incorporates therein, for example, a motor as adriving source. The chuck 100 is configured to be rotated around avertical axis by the rotator 103 via the air bearing 101 therebetween.The slider table 102 is configured to be moved by a horizontally movingmember 104, which is provided at a bottom surface side thereof, along arail 105 which is provided on a base 106 and elongated in the Y-axisdirection. Further, though not particularly limited, a driving source ofthe horizontally moving member 104 may be, for example, a linear motor.

A laser head 110 is provided above the chuck 100. The laser head 110 hasa lens 111. The lens 111 is a cylindrical member provided on a bottomsurface of the laser head 110, and is configured to radiate the laserlight to the processing target wafer W held by the chuck 100. In thepresent exemplary embodiment, the laser head 110 is shared by aperipheral modifying device and an internal modifying device.

The laser head 110 is further equipped with a non-illustrated LCOS(Liquid Crystal on Silicon). The LCOS serves as a spatial lightmodulator, and is configured to output the laser light after modulatingit. To be specific, the LCOS is capable of controlling a focal positionand a phase of the laser light, and thus capable of adjusting a shapeand a number (a split number) of the laser light radiated to theprocessing target wafer W.

Further, the laser head 110 is configured to concentrate and radiate thelaser light having a wavelength featuring transmissivity for theprocessing target wafer W to a required position within the processingtarget wafer W as high-frequency laser light in a pulse shape oscillatedfrom a laser light oscillator (not shown). Accordingly, a portion withinthe processing target wafer W to which the laser light is concentratedis modified, so that a peripheral modification layer, a splitmodification layer and an internal modification layer are formed.

The laser head 110 is supported at a supporting member 120. The laserhead 110 is configured to be moved up and down by an elevating mechanism130 along a vertically elongated rail 121. Further, the laser head 110is configured to be moved in the Y-axis direction by a moving mechanism131. Each of the elevating mechanism 130 and the moving mechanism 131 issupported at a supporting column 132.

Above the chuck 100, a macro-camera 140 and a micro-camera 150 areprovided at a positive Y-axis side of the laser head 110. For example,the macro-camera 140 and the micro-camera 150 are formed as one body,and the macro-camera 140 is provided at a positive Y-axis side of themicro-camera 150. The macro-camera 140 and the micro-camera 150 areconfigured to be moved up and down by an elevating mechanism 160, andalso configured to be moved in the Y-axis direction by a movingmechanism 161.

The macro-camera 140 images an outer end portion of the processingtarget wafer W (combined wafer T). The macro-camera 140 is equippedwith, for example, a coaxial lens, and radiates visible light, forexample, red light and receives reflection light from a target object.For example, the macro-camera 140 has an image magnification of twotimes.

The micro-camera 150 images a peripheral portion of the processingtarget wafer W and also images a boundary between the bonding region Aaand the non-bonding region Ab. The micro-camera 150 is equipped with,for example, a coaxial lens, and radiates infrared light (IR light) andreceives reflection light from a target object. By way of example, themicro-camera 150 has an image magnification of 10 times. A field of viewof the micro-camera 150 is about ⅕ of a field of view of themacro-camera 140, and a pixel size of the micro-camera 150 is about ⅕ ofa pixel size of the macro-camera 140.

Now, the aforementioned periphery removing apparatus 61 will beexplained. FIG. 6 is a plan view illustrating a schematic configurationof the periphery removing apparatus 61. FIG. 7 is a side viewillustrating the schematic configuration of the periphery removingapparatus 61.

The periphery removing apparatus 61 is equipped with a chuck 170, asanother substrate holder, configured to hold the combined wafer T on atop surface thereof. The chuck 170 is configured to attract and hold thesupport wafer S in the state that the processing target wafer W isplaced at an upper side and the support wafer S is placed at a lowerside. Further, the chuck 170 is configured to be rotated around avertical axis by a rotating mechanism 171.

Provided above the chuck 170 is a pad 180, as a periphery removing unit,configured to transfer the processing target wafer W while holding theperipheral portion We thereof. The pad 180 is connected with a suctionmechanism (not shown) such as, but not limited to, a vacuum pump, andthe pad 180 is configured to attract and hold the peripheral portion Weon a bottom surface thereof. The pad 180 is equipped with an elevatingmechanism 181 configured to move the pad 180 in a vertical direction anda moving mechanism 182 configured to move the pad 180 in horizontaldirections (the X-axis direction and the Y-axis direction).

A detector 190 is provided above the chuck 170 to detect whether theperipheral portion We is removed from the processing target wafer W. Thedetector 190 detects presence or absence of the peripheral portion We inthe processing target wafer W which is held by the chuck 170 and fromwhich the peripheral portion We is removed. By way of example, a sensormay be used as the detector 190. The sensor may be, by way ofnon-limiting example, a line type laser displacement meter, and itdetects the presence or absence of the peripheral portion We byradiating laser to the peripheral portion of the combined wafer T(processing target wafer W) and measuring a thickness of the combinedwafer T. However, the way how to detect the presence or absence of theperipheral portion We by the detector 190 is not limited thereto. Forexample, the detector 190 may detect the presence or absence of theperipheral portion We by imaging the combined wafer T (processing targetwafer W) with, for example, a line camera.

Further, a collector (not shown) configured to collect the peripheralportion We transferred by the pad 180 is provided under the chuck 170.The collector receives and collects the peripheral portion We attractedto and held by the pad 180.

Now, the transfer arm 71 of the aforementioned wafer transfer device 70will be described. FIG. 8 is a longitudinal cross sectional viewillustrating a schematic configuration of the transfer arm 71.

The transfer arm 71, as a substrate separating unit and a transfer unit,is equipped with a circular attraction plate 200 having a diameterlarger than a diameter of the combined wafer T. A holder 210 configuredto hold the central portion Wc of the processing target wafer W isprovided in a bottom surface of the attraction plate 200.

A suction line 211 for suctioning the central portion Wc is connected tothe holder 210, and the suction line 211 is connected to a suctionmechanism 212 such as, but not limited to, a vacuum pump. The suctionline 211 is provided with a pressure sensor 213 configured to measure asuction pressure. Though a configuration of the pressure sensor 213 isnot particularly limited, a diaphragm pressure sensor may be used.

A rotating mechanism 220 configured to rotate the attraction plate 200around a vertical axis is provided on a top surface of the attractionplate 200. The rotating mechanism 220 is supported at a supportingmember 221. Further, the supporting member 221 (rotating mechanism 220)is supported at the arm member 72.

Now, a wafer processing according to a first exemplary embodimentperformed by using the wafer processing system 1 configured as describedabove will be discussed. FIG. 9 is a flowchart illustrating mainprocesses of the wafer processing. FIG. 10A to FIG. 10F are explanatorydiagrams illustrating the main processes of the wafer processing. In thepresent exemplary embodiment, the combined wafer T is previously formedby bonding the processing target wafer W and the support wafer S in thebonding apparatus (not shown) at the outside of the wafer processingsystem 1.

First, the cassette Ct accommodating therein the multiple number ofcombined wafers T shown in FIG. 10A is placed on the cassette placingtable 10 of the carry-in/out station 2.

Then, the combined wafer T is taken out of the cassette Ct by the wafertransfer device 20, and transferred into the transition device 30.Subsequently, the combined wafer T is taken out of the transition device30 by the wafer transfer device 50, and transferred into the modifyingapparatus 60. In the modifying apparatus 60, a peripheral modificationlayer M1 and a split modification layer M2 are formed inside theprocessing target wafer W in sequence as illustrated in FIG. 10B(processes A1 and A2 of FIG. 9), and, also, an internal modificationlayer M3 is formed as illustrated in FIG. 10C (process A3 of FIG. 9).The peripheral modification layer M1 serves as a starting point when theperipheral portion We is removed in the edge trimming. The splitmodification layer M2 serves as starting point when the peripheralportion We to be removed is broken into smaller pieces. The internalmodification layer M3 serves as a starting point for thinning theprocessing target wafer W.

FIG. 11A to FIG. 11E are explanatory diagrams illustrating mainprocesses of a modifying processing performed by the modifying apparatus60. First, as shown in FIG. 11A, the chuck 100 (slider table 102) ismoved to a carry-in/out position P1. Then, the combined wafer T iscarried in from the wafer transfer device 50 to be held by the chuck100.

Then, the chuck 100 is moved to a macro-alignment position P2, as shownin FIG. 11B. The macro-alignment position P2 is a position where themacro-camera 140 is capable of imaging the outer end portion of theprocessing target wafer W.

Thereafter, the outer end portion of the processing target wafer W isimaged by the macro-camera 140 in 360 degrees in a circumferentialdirection of the processing target wafer W. The obtained image isoutputted to the control device 90 from the macro-camera 140.

In the control device 90, the first eccentric amount between the centerCc of the chuck 100 and the center Cw of the processing target wafer Wis calculated from the image obtained by the macro-camera 140. Further,in the control device 90, a moving amount of the chuck 100 is calculatedbased on the first eccentric amount to correct a Y-axis component of thefirst eccentric amount. The chuck 100 is moved in the Y-axis directionbased on the calculated moving amount, and then moved to amicro-alignment position P3, as shown in FIG. 11C. The micro-alignmentposition P3 is a position where the micro-camera 150 is capable ofimaging the peripheral portion of the processing target wafer W. Here,the field of view of the micro-camera 150 is smaller (about ⅕) than thefield of view of the macro-camera 140, as stated above. Thus, if theY-axis component of the first eccentric amount is not corrected, theperipheral portion of the processing target wafer W may not be includedin an angle of view of the micro-camera 150, resulting in a failure toimage the peripheral portion of the processing target wafer W with themicro-camera 150. For the reason, the correction of the Y-axis componentbased on the first eccentric amount is performed to move the chuck 100to the micro-alignment position P3.

Subsequently, the boundary between the bonding region Aa and thenon-bonding region Ab is imaged by the micro-camera 150 in 360 degreesin the circumferential direction of the processing target wafer W. Theobtained image is outputted to the control device 90 from themicro-camera 150.

In the control device 90, the second eccentric amount between the centerCc of the chuck 100 and the center Ca of the bonding region Aa iscalculated from the image obtained by the micro-camera 150. Further, inthe control device 90, the position of the chuck 100 with respect to theperipheral modification layer M1 is decided based on the secondeccentric amount such that the center of the chuck 100 and the center ofthe bonding region Aa are coincident with each other. As stated above,though the non-bonding region Ab is formed before the processing targetwafer W and the support wafer S are bonded, a center of this non-bondingregion Ab (center Ca of the bonding region Aa) may be deviated from thecenter of the processing target wafer W. However, as in the presentexemplary embodiment, by adjusting the position of the chuck 100 withrespect to the peripheral modification layer M1 based on the secondeccentric amount, the deviation of the non-bonding region Ab can becorrected.

Subsequently, the chuck 100 is moved to a modifying position P4, asshown in FIG. 11D. The modifying position P4 is a position where thelaser head 110 radiates the laser light to the processing target wafer Wto thereby form the peripheral modification layer M1. Further, in thepresent exemplary embodiment, the modifying position P4 is identical tothe micro-alignment position P3.

Thereafter, as illustrated in FIG. 12 and FIG. 13, by radiating laserlight L1 (laser light L1 for periphery) from the laser head 110, theperipheral modification layer M1 is formed at the boundary between theperipheral portion We and the central portion We of the processingtarget wafer W (process A1 of FIG. 9). The shape and the number of thelaser light L1 are adjusted by the LCOS. To elaborate, to form theperipheral modification layer M1 to be described later, the shape of thelaser light L1 is adjusted as the focal point and the phase thereof arecontrolled. In the present exemplary embodiment, the number of the laserlight L1 is one.

The peripheral modification layer M1 formed by the laser light L1 iselongated in a thickness direction and has an aspect ratio with avertically longer side. A lower end of the peripheral modification layerM1 is located above a target surface (indicated by a dashed line in FIG.12) of the processing target wafer W after being thinned. That is, adistance H1 between the lower end of the peripheral modification layerM1 and the front surface Wa of the processing target wafer W is largerthan a target thickness H2 of the processing target wafer W after beingthinned. In this case, the peripheral modification layer M1 does notremain in the processing target wafer W after being thinned. Further,within the processing target wafer W, a crack C1 develops from theperipheral modification layer M1, and reaches the front surface Wa andthe rear surface Wb.

Further, the peripheral modification layer M1 is formed at an inner sidethan an outer end portion of the bonding region Aa in the diametricaldirection. Even if the peripheral modification layer M1 is formed whilebeing deviated from the outer end portion of the bonding region Aa dueto, for example, a processing error or the like when the peripheralmodification layer M1 is formed by the laser light L1 from the laserhead 110, the peripheral modification layer M1 can be suppressed frombeing formed at an outer side than the outer end portion of the bondingregion Aa in the diametrical direction. Here, if the peripheralmodification layer M1 is formed at the outer side than the outer endportion of the bonding region Aa in the diametrical direction, theprocessing target wafer W may not be firmly bonded to the support waferS after the peripheral portion We is removed. In the present exemplaryembodiment, however, this state of the processing target wafer W can besecurely suppressed.

Further, the present inventors have conducted researches and found outthat the peripheral portion We can be appropriately removed if adistance D between the peripheral modification layer M1 and the outerend portion of the bonding region Aa is sufficiently small. Thisdistance D is desirably within 500 μm and, more desirably, within 50 μm.

Here, in the control device 90, the position of the chuck 100 is decidedbased on the second eccentric amount. In the process Al, to locate thechuck 100 at the decided position, the chuck 100 is rotated by therotator 103 and moved in the Y-axis direction by the horizontally movingmember 104 such that the center of the chuck 100 and the center of thebonding region Aa are coincident. At this time, the rotating of thechuck 100 and the moving of the chuck 100 in the Y-axis direction aresynchronized. By performing the completely synchronized control asstated above, the chuck 100 can be moved to the decided positionappropriately with little error.

While rotating and moving the chuck 100 (processing target wafer W) asdescribed above, the laser light L1 is radiated to the inside of theprocessing target wafer W from the laser head 110. That is, whilecorrecting the second eccentric amount, the peripheral modificationlayer M1 is formed. The peripheral modification layer M1 is formed in aring shape to be concentric with the bonding region Aa. That is, thedistance D between the peripheral modification layer M1 and the outerend portion of the bonding region Aa shown in FIG. 12 can be madeconstant. Thus, in the periphery removing apparatus 61, the peripheralportion We can be appropriately removed, starting from the peripheralmodification layer M1.

Further, in the present exemplary embodiment, if the second eccentricamount includes an X-axis component, this X-axis component is correctedby rotating the chuck 100 while moving it in the Y-axis direction.Meanwhile, if the second eccentric amount does not include the X-axiscomponent, the chuck 100 only needs to be moved in the Y-axis directionwithout being rotated.

Thereafter, the laser head 110 is moved in the Y-axis direction, and byradiating laser light L2 (laser light L2 for split) from the laser head110, the split modification layer M2 is formed at an outer side than theperipheral modification layer M1 in the diametrical direction (processA2 of FIG. 9), as illustrated in FIG. 14 and FIG. 15. At this time, thelaser light radiated from the laser head 110 is switched to the laserlight L2 from the laser light L1 by the LCOS, and the shape and thenumber of the laser light L2 are adjusted. To be specific, as a focalposition and a phase of the laser light L2 are adjusted, the shape ofthe laser light L2 is adjusted to form the split modification layer M2to be described later. Further, in the present exemplary embodiment, thenumber of the laser light L2 is one.

The split modification layer M2 is elongated in the thickness directionand has an aspect ratio with a vertically longer side, the same as theperipheral modification layer M1. Further, in the present exemplaryembodiment, the split modification layer M2 is formed on a level withthe peripheral modification layer M1. In addition, a crack C2 developsfrom the split modification layer M2 and reaches the front surface Waand the rear surface Wb.

Furthermore, by forming multiple split modification layers M2 and cracksC2 at a pitch of several micrometers (μm) in the diametrical direction,a single line-shaped split modification layer M2 elongated outwards fromthe peripheral modification layer M1 in the diametrical direction isformed, as shown in FIG. 15. Further, in the shown example, theline-shaped split modification layer M2 elongated in the diametricaldirection is formed at eight different positions. However, the number ofthe split modification layers M2 is not particularly limited. As long asthe split modification layers M2 are formed at two different positionsat least, the peripheral portion We can be removed. In this case, whenremoving the peripheral portion We in the edge trimming, this peripheralportion We is separated starting from the ring-shaped peripheralmodification layer M1 to be split into multiple pieces by the splitmodification layers M2. Accordingly, the peripheral portion We to beremoved is broken into smaller pieces, and thus can be removed moreeasily.

Moreover, though the laser head 110 is moved in the Y-axis direction toform the split modification layer M2 in the present exemplaryembodiment, the chuck 100 may be moved in the Y-axis direction instead.

Subsequently, as depicted in FIG. 16 and FIG. 17, by radiating laserlight L3 (laser light L3 for internal plane) from the laser head 110,the internal modification layer M3 is formed along a plane direction ofthe processing target wafer W (process A3 of FIG. 9). At this time, thelaser light radiated from the laser head 110 is switched to the laserlight L3 from the laser light L2 by the LCOS, and the shape and thenumber of the laser light L3 are adjusted. To be specific, as a focalposition and a phase of the laser light L3 are adjusted, the shape ofthe laser light L3 is adjusted to form the internal modification layerM3 to be described later. Further, in the present exemplary embodiment,the number of the laser light L3 is one. In addition, black arrows shownin FIG. 17 indicate a rotation direction of the chuck 100, the same asin the following description.

A lower end of the internal modification layer M3 is located above thetarget surface (indicated by a dashed line in FIG. 16) of the processingtarget wafer W after being thinned. That is, a distance H3 between thelower end of the internal modification layer M3 and the front surface Waof the processing target wafer W is slightly larger than the targetthickness H2 of the processing target wafer W after being thinned.Within the processing target wafer W, a crack C3 develops from theinternal modification layer M3 along the plane direction.

In the process A3, while rotating the chuck 100 (processing target waferW) and moving the laser head 110 in the Y-axis direction from theperipheral portion of the processing target wafer W toward the centralportion thereof, the laser light L3 is radiated from the laser head 110to the inside of the processing target wafer W. As a result, theinternal modification layer M3 is formed in a spiral shape from an outerside to an inner side within the surface of the processing target waferW.

Further, in the present exemplary embodiment, though the laser head 110is moved in the Y-axis direction to form the internal modification layerM3, the chuck 100 may be moved in the Y-axis direction instead.

Subsequently, the chuck 100 is moved to the carry-in/out position P1, asshown in FIG. 11E. Then, the combined wafer T is taken out by the wafertransfer device 70.

As stated above, in the modifying apparatus 60, the formation of theperipheral modification layer M1 in the process Al and the formation ofthe internal modification layer M3 in the process A3 are performed inthis sequence. Here, if the internal modification layer M3 is formedbefore the peripheral modification layer Ml, the processing target waferW may be expanded or bent. For example, if the internal modificationlayer M3 is formed, the crack C3 develops in the plane direction of theprocessing target wafer W. Then, a stress is applied to the crack C3,causing the processing target wafer W to be expanded in the planedirection. If the size of this expansion differs at different positionsin the plane direction of the processing target wafer W, the processingtarget wafer W may be locally separated. In such a case, a height of theprocessing target wafer W may become non-uniform within a surfacethereof, which causes the processing target wafer W to be bent. If theprocessing target wafer W is expanded or bent, the peripheralmodification layer M1 cannot be formed at an appropriate position. As aresult, the peripheral portion We cannot be removed appropriately,resulting in a failure to achieve a required product quality. In thepresent exemplary embodiment, however, by forming the peripheralmodification layer M1 and the internal modification layer M3 in thissequence, the expansion or the bending of the processing target wafer Wcan be suppressed.

Then, the combined wafer T is transferred into the periphery removingapparatus 61 by the wafer transfer device 70. In the periphery removingapparatus 61, the peripheral portion We of the processing target wafer Wis removed starting from the peripheral modification layer M1 (processA4 of FIG. 9), as illustrated in FIG. 10D. In the process A4, asillustrated in FIG. 18, the pad 180 is lowered by the elevatingmechanism 181 to attract and hold the peripheral portion We, and, then,the pad 180 is raised. As a result, the peripheral portion We held bythe pad 180 is separated from the processing target wafer W, startingfrom the peripheral modification layer M1. At this time, the peripheralportion We is separated while being broken into smaller pieces startingfrom the split modification layers M2. Further, the removed peripheralportion We is collected from the pad 180 into the collector (not shown).

Thereafter, the combined wafer T is transferred into the processingapparatus 80 by the wafer transfer device 70. First, in the processingapparatus 80, when the combined wafer T is delivered from the transferram 71 onto the chuck 81, the rear surface Wb side of the processingtarget wafer W (hereinafter, referred to as “rear surface wafer Wb1”) isseparated starting from the internal modification layer M3 (process A5of FIG. 9), as illustrated in FIG. 10E.

In the process A5, the support wafer S is attracted to and held by thechuck 81 while the processing target wafer W is attracted to and held bythe attraction plate 200 of the transfer arm 71, as shown in FIG. 19A.Then, the attraction plate 200 is rotated, and the rear surface waferWb1 is cut along the internal modification layer M3. Thereafter, asshown in FIG. 19B, the attraction plate 200 is raised in the state thatthe rear surface wafer Wb1 is attracted to and held by the attractionplate 200, so that the rear surface wafer Wb1 is separated from theprocessing target wafer W. At this time, by measuring a pressure forsuctioning the rear surface wafer Wb1 with the pressure sensor 213,presence or absence of the rear surface wafer Wb1 is detected. Thus, itcan be checked whether the rear surface wafer Wb1 is separated from theprocessing target wafer W. Further, if the rear surface wafer Wb1 can beseparated only by raising the attraction plate 200 as shown in FIG. 19B,the rotating of the attraction plate 200 shown in FIG. 19A can beomitted. Further, the separated rear surface wafer Wb1 is collected tothe outside of the wafer processing system 1.

Subsequently, as shown in FIG. 10F, the rear surface Wb of theprocessing target wafer W held by the chuck 81 is ground, and theinternal modification layer M3 and the peripheral modification layer M1left on the rear surface Wb are removed (process A6 of FIG. 9). In theprocess A6, by rotating the processing target wafer W and the grindingwhetstone in the state that the rear surface Wb is in contact with thegrinding whetstone, the rear surface Wb is ground. Further, the rearsurface Wb of the processing target wafer W may be then cleaned by acleaning liquid from a cleaning liquid nozzle (not shown).

Thereafter, the combined wafer T is transferred to the cleaningapparatus 41 by the wafer transfer device 70. In the cleaning apparatus41, the ground rear surface Wb of the processing target wafer W isscrub-cleaned (process A7 of FIG. 9). Further, in the cleaning apparatus41, the rear surface Sb of the support wafer S as well as the rearsurface Wb of the processing target wafer W may be cleaned.

Afterwards, the combined wafer T is transferred to the etching apparatus40 by the wafer transfer device 50. In the etching apparatus 40, therear surface Wb of the processing target wafer W is wet-etched by thechemical liquid (process A8 of FIG. 9). A grinding mark may be formed onthe rear surface Wb ground by the aforementioned processing apparatus80. In the process A8, the grinding mark can be removed by performingthe wet-etching, so that the rear surface Wb can be flattened.

Then, the combined wafer T after being subjected to all the requiredprocessings is transferred to the transition device 30 by the wafertransfer device 50, and then transferred into the cassette Ct on thecassette placing table 10 by the wafer transfer device 20. Accordingly,a series of the processes of the wafer processing in the waferprocessing system 1 is ended.

Further, according to the present exemplary embodiment, the edgetrimming is carried out by removing the peripheral portion We startingfrom the peripheral modification layer M1, and the thinning of theprocessing target wafer W is carried out by separating the rear surfacewafer Wb1 starting from the internal modification layer M3. Since thelaser head 110 used to form the peripheral modification layer M1 and theinternal modification layer M3 is not easily degraded with a lapse oftime, less consumables are used. Therefore, a frequency of maintenancecan be reduced. Furthermore, since these processings are dry-processesusing the laser, disposing of grinding water and waste water is notrequired. Therefore, a running cost can be reduced. Hence, as comparedto conventional edge trimming and thinning by grinding, the running costcan be reduced.

Furthermore, in the present exemplary embodiment, although the rearsurface Wb is ground in the process A6, this grinding needs to beperformed just to remove the internal modification layer M3 and theperipheral modification layer Ml, and the grinding amount thereof issmall (about several tens of micrometers). In contrast, in case ofgrinding the rear surface Wb to thin the processing target wafer W as inthe prior art, the grinding amount thereof is large (e.g., 700 μm), andthe grinding whetstone is abraded greatly. Thus, in the presentexemplary embodiment, the frequency of the maintenance can be furtherreduced.

Further, according to the present exemplary embodiment, the peripheralmodification layer M1 and the internal modification layer M3 are formedwithin the processing target wafer W in this sequence. As stated above,if the internal modification layer M3 is formed first, the processingtarget wafer W may be expanded or bent. In the present exemplaryembodiment, however, the expansion or the bending of the processingtarget wafer W can be suppressed. As a result, the peripheral portion Wecan be removed appropriately, and, thus, a required product quality canbe obtained.

In addition, according to the present exemplary embodiment, theperipheral modification layer M1, the split modification layer M2 andthe internal modification layer M3 can be formed by adjusting the shapesof the laser lights L1 to L3 by using the single laser head 110. Thatis, even when directions in which the modification layers are elongatedare different or even when required processing qualities are different,the appropriate shape of the laser light can be selected by using thesingle laser head 110. Since a modification layer having any requiredshape can be formed, the degree of freedom in forming the modificationlayer can be improved. Further, since a footprint of the apparatus canbe reduced, space can be saved. Furthermore, since the apparatusconfiguration is simplified, an apparatus cost can be cut. As statedabove, in the present exemplary embodiment, the pre-treatment of thethinning and the edge trimming of the processing target wafer W can beperformed efficiently.

Furthermore, in the above-described exemplary embodiments, though thelaser lights L1 to L3 having the different shapes are radiated by thesingle laser head 110, it is desirable that the laser head 110 iscorrected (calibrated) before the combined wafer T as a processingtarget is carried into the modifying apparatus 60. To be more specific,it is desirable to correct the laser head 110 before the combined waferT is held on the chuck 100. In this case, since the correction upon thelaser head 110 need not be performed during the modifying processingupon the single processing target wafer W, a time required for theswitching of the laser lights L1 to L3 can be saved. As a result, athroughput of the wafer processing can be improved.

Moreover, in the above-described exemplary embodiments, although thesingle laser light L1 is radiated to the inside of the processing targetwafer W from the laser head 110 to form the peripheral modificationlayer M1, multiple laser lights L1 may be radiated. In this case, a timetaken to form the peripheral modification layer M1 can be shortened, sothat the throughput of the wafer processing can be further improved.Likewise, although the single laser light L3 is radiated to the insideof the processing target wafer W from the laser head 110 to form theinternal modification layer M3, multiple laser lights L3 may beradiated. In this case, a time taken to form the internal modificationlayer M3 can be shortened, so that the throughput of the waferprocessing can be further improved.

In the above-described exemplary embodiment, the peripheral portion Weis removed by using the pad 180 in the periphery removing apparatus 61,and the processing target wafer W is separated by using the transfer arm71 in the processing apparatus 80. However, the removing of theperipheral portion We and the transfer arm 71 may be performed withinone and the same apparatus. By way of example, in the periphery removingapparatus 61, an attraction plate 230 as a substrate separating unit maybe further provided above the chuck 170, as depicted in FIG. 20. Theattraction plate 230 has the same configuration as the attraction plate200 of the transfer arm 71, and has a disk shape with a diameter largerthan the diameter of the combined wafer T. The attraction plate 230 isconnected with a suction mechanism (not shown) such as, but not limitedto, a vacuum pump, and is configured to attract and hold the rearsurface Wb of the processing target wafer W on a bottom surface thereof.The attraction plate 230 is equipped with an elevating mechanism 231configured to move the attraction plate 230 in a vertical direction anda rotating mechanism 232 configured to rotate the attraction plate 230around a vertical axis.

In this configuration, after the peripheral portion We is removed by thepad 180 in the process A4, the processing target wafer W is separated bythe attraction plate 230 in the process A5. In the process A5, the rearsurface Wb of the processing target wafer W is attracted to and held bythe attraction plate 230. Then, by rotating the attraction plate 230,the rear surface wafer Wb1 is cut starting from the internalmodification layer M3. Then, by raising the attraction plate 230 in thestate that the rear surface wafer Wb1 is attracted to and held by theattraction plate 230, the rear surface wafer Wb1 is separated from theprocessing target wafer W. Here, if the rear surface wafer Wb1 can beseparated just by raising the attraction plate 230, the attraction plate230 may not be rotated.

Furthermore, the attraction plate 230 may attract and hold the centralportion Wc and the peripheral portion We of the processing target waferW individually. To be specific, a central holder (not shown) configuredto hold the central portion Wc and a peripheral holder (not shown)configured to hold the peripheral portion We may be provided in thebottom surface of the attraction plate 230. The central holder and theperipheral holder are connected to suction mechanisms (not shown)respectively, and by switching the central holder and the peripheralholder, the central portion Wc and the peripheral portion We can beattracted to and held by the attraction plate 230 individually. In sucha case, the removing of the peripheral portion We in the process A4 andthe separating of the processing target wafer W in the process A5 areperformed by the attraction plate 230. Further, in the present example,the pad 180, the elevating mechanism 181 and the moving mechanism 182are omitted.

In the present exemplary embodiment as well, the removing of theperipheral portion We of the processing target wafer W and theseparating of the processing target wafer W can be performedappropriately. Further, since the removing and the separating can beperformed in the same apparatus, a throughput of the wafer processingcan be improved.

Here, in the present exemplary embodiment, the peripheral modificationlayer M1 and the internal modification layer M3 are formed within theprocessing target wafer W in this sequence. Meanwhile, when the internalmodification layer M3 is formed, the processing target wafer W may beexpanded. In such a case, the peripheral portion We may be peeled offdue to the expansion of the processing target wafer W, and the peeledperipheral portion We may have an adverse influence upon a drivingsystem such as the rotator 103 or the horizontally moving member 104within the modifying apparatus 60. In view of this, it is desirable toprovide a countermeasure to the peeling of the peripheral portion We. Asthis countermeasure, the following two methods are considered, forexample.

The first way to suppress the peeling of the peripheral portion We is topush the peripheral portion We physically. By way of example, asillustrated in FIG. 21, a plurality of cylindrical peripheral holders240 configured to be brought into contact with an edge of the processingtarget wafer W may be provided. Alternatively, as depicted in FIG. 22,for example, a plurality of rectangular parallelepiped peripheralholders 241 configured to be brought into contact with the edge of theprocessing target wafer W may be provided. Each of the peripheralholders 240 (241) is configured to be movable in a vertical directionand a horizontal direction by a moving mechanism (not shown). Theperipheral holder 240 and the peripheral holder 241 are different fromeach other in that the former comes into a point contact with theprocessing target wafer W whereas the latter comes into a line contactwith the processing target wafer W. Whichever is used, however, thepeeling of the peripheral portion We can be suppressed. Further, theperipheral holders 240 (241) need to be in contact with the edge of theprocessing target wafer W when the internal modification layer M3 isformed only. Other than that, the peripheral holders 240 (241) may bekept retreated from the processing target wafer W.

The second way to suppress the peeling of the peripheral portion We isto allow the crack C1 which develops from the peripheral modificationlayer M1 in the thickness direction of the processing target wafer W toprogress to the front surface Wa only. By adjusting the shape of thelaser light L1 radiated from the laser head 110, the crack C1 is allowedto reach the front surface Wa only without reaching the rear surface Wb,as illustrated in FIG. 23A. Likewise, when forming the splitmodification layer M2, the crack C2 is made to reach the front surfaceWa only without reaching the rear surface Wb. In this case, even if theinternal modification layer M3 is formed later as illustrated in FIG.23B, the peripheral portion We is not peeled off the processing targetwafer W.

Now, a wafer processing according to a second exemplary embodiment willbe described. FIG. 24 is a flowchart illustrating main processes of thewafer processing. FIG. 25A to FIG. 25E are explanatory diagramsillustrating the main processes of the wafer processing.

Although the removing of the peripheral portion We and the separating ofthe processing target wafer W are performed separately in the firstexemplary embodiment, they are performed at the same time in the secondexemplary embodiment. The removing of the peripheral portion We and theseparating of the processing target wafer W are performed in, forexample, the processing apparatus 80 by using the transfer arm 71serving as a removing/separating unit. Further, the transfer arm 71according to the present exemplary embodiment holds the entireprocessing target wafer W, that is, the central portion We and theperipheral portion We thereof. Since the removing of the peripheralportion We is performed by using the transfer arm 71, the peripheryremoving apparatus 61 may be omitted in the wafer processing system 1according to the second exemplary embodiment.

In the wafer processing according to the second exemplary embodiment,the combined wafer T shown in FIG. 25A is first transferred into themodifying apparatus 60. In the modifying apparatus 60, a peripheralmodification layer M10 is formed in the processing target wafer W(process B1 of FIG. 24), as shown in FIG. 25B, and an internalmodification layer M30 is formed in the processing target wafer W(process B2 of FIG. 24), as shown in FIG. 25C.

Here, the way how to form the peripheral modification layer M10 in theprocess B1 is the same as the process Al. However, as compared to thecrack C1 from the peripheral modification layer M1 in FIG. 1013 whichreaches both the front surface Wa and the rear surface Wb, a crack C10from the peripheral modification layer M10 reaches only the frontsurface Wa without reaching the rear surface Wb.

Further, the way how to form the internal modification layer M30 in theprocess B2 is the same as the process A2. However, as compared to thecrack C3 from the internal modification layer M3 shown in FIG. 10C whichdevelops up to the edge of the processing target wafer W in the planedirection, a crack C30 from the internal modification layer M30progresses only to an inner side than the peripheral modification layerM1.

Subsequently, the combined wafer T is transferred to the processingapparatus 80 by the wafer transfer device 70. In the processingapparatus 80, when the combined wafer T is delivered onto the chuck 81from the transfer arm 71, the rear surface Wb side of the processingtarget wafer W (hereinafter, referred to as “rear surface wafer Wb2”) isseparated starting from the peripheral modification layer M10 and theinternal modification layer M30 (process B3 of FIG. 24), as illustratedin FIG. 1125D.

In the process B3, while attracting and holding the processing targetwafer W by the attraction plate 200 of the transfer arm 71, the supportwafer S is attracted to and held by the chuck 81, as shown in FIG. 26A.Then, the attraction plate 200 is rotated, and the rear surface waferWb2 is cut along the peripheral modification layer M10 and the internalmodification layer M30. Thereafter, as shown in FIG. 26B, by raising theattraction plate 200 in the state that the rear surface wafer Wb2 isattracted to and held by the attraction plate 200, the rear surfacewafer Wb2 is separated from the processing target wafer W. As statedabove, in the process B3, the rear surface wafer Wb2 and the peripheralportion We are separated as one body. That is, the removing of theperipheral portion We and the separating of the processing target waferW are performed at the same time.

Subsequently, as shown in FIG. 25E, the rear surface Wb of theprocessing target wafer W is ground (process B4 of FIG. 24), andcleaning of the rear surface Wb in the cleaning apparatus 41 (process B5of FIG. 24) and wet-etching of the rear surface Wb in the etchingapparatus 40 (process B6 of FIG. 24) are performed in sequence. Then,the wafer processing in the wafer processing system 1 including theaforementioned series of processes is completed.

In the present exemplary embodiment as well, since the peripheralmodification layer M1 and the internal modification layer M3 are formedwithin the processing target wafer W in this sequence, the same effectas obtained in the first exemplary embodiment can be achieved. Further,since the crack from the peripheral modification layer M10 does notreach the rear surface Wb, the peripheral portion We is not peeled offeven if the processing target wafer W is expanded when the internalmodification layer M30 is formed. Further, to suppress the peeling ofthe peripheral portion We more securely, it may be possible to providethe peripheral holders 240 or 241 as shown in FIG. 21 or FIG. 22.

In the above-described exemplary embodiment, although the removing ofthe peripheral portion We and the separating of the processing targetwafer W are performed by using the transfer arm 71, they may beperformed by using a separate device. By way of example, in the waferprocessing system 1, a removing/separating apparatus 300 shown in FIG.27 may be provided instead of the periphery removing apparatus 61.

The removing/separating apparatus 300 is equipped with a chuck 310 asanother substrate holder, which is configured to hold the combined waferT on a top surface thereof. The chuck 310 is configured to attract andhold the support wafer S in the state that the processing target wafer Wis placed at an upper side and the support wafer S is placed at a lowerside. Further, the chuck 310 is configured to be rotated around avertical axis by a rotating mechanism 311.

An attraction plate 320 as a removing/separating unit is provided abovethe chuck 310. The attraction plate 320 has the same configuration asthe attraction plate 200 of the transfer arm 71, and has a disk shapewith a diameter larger than that of the combined wafer T. The attractionplate 320 is connected with a suction mechanism (not shown) such as, butnot limited to, a vacuum pump, and the attraction plate 320 isconfigured to attract and hold the rear surface Wb of the processingtarget wafer W on a bottom surface thereof. The attraction plate 320 isequipped with an elevating mechanism 321 configured to move theattraction plate 320 in a vertical direction and a rotating mechanism322 configured to rotate the attraction plate 320 around a verticalaxis.

In this configuration, the rear surface Wb of the processing targetwafer W is attracted to and held by the attraction plate 320. Then, byrotating the attraction plate 320, the rear surface wafer Wb2 is cutalong the peripheral modification layer M1 and the internal modificationlayer M3. Thereafter, by raising the attraction plate 320 in the statethat the rear surface wafer Wb2 is attracted to and held by theattraction plate 320, the rear surface wafer Wb2 is separated from theprocessing target wafer W. In the removing/separating apparatus 300according to the present exemplary embodiment as well, the removing ofthe peripheral portion We of the processing target wafer W and theseparating of the processing target wafer W can be carried outappropriately.

Now, a wafer processing according to a third exemplary embodiment willbe discussed. FIG. 28 is a flowchart illustrating main processes of thewafer processing. FIG. 29A to FIG. 29F are explanatory diagramsillustrating the main processes of the wafer processing.

In the first exemplary embodiment, the peripheral portion We is removedafter the internal modification layer M3 is formed. In the thirdexemplary embodiment, however, an internal modification layer M31 isformed after the peripheral portion We is removed. That is, in the thirdexemplary embodiment, formation of a peripheral modification layer M11,removal of the peripheral portion We and formation of the internalmodification layer M31 are performed in this sequence. The formation ofthe peripheral modification layer M11 and the formation of the internalmodification layer M31 are performed by the modifying apparatus 60. If,however, the removing of the peripheral portion We is performed at theoutside of the modifying apparatus 60, a throughput would be degraded.Thus, in the present exemplary embodiment, the removing of theperipheral portion We is performed within the modifying apparatus 60 byusing the transfer arm 71 as a periphery removing unit. In this way,since the peripheral portion We is removed by using the transfer arm 71,the periphery removing apparatus 61 may be omitted in the waferprocessing system 1 according to the present exemplary embodiment.Further, the transfer arm 71 also serves as a substrate separating unit,as will be described later.

As depicted in FIG. 30, the transfer arm 71 is equipped with anattraction plate 400 having a disk shape with a diameter larger thanthat of the processing target wafer W. A central holder 410 configuredto hold the central portion Wc of the processing target wafer W and aperipheral holder 420 configured to hold the peripheral portion We ofthe processing target wafer W are provided in the bottom surface of theattraction plate 400.

The central holder 410 is connected to a suction line 411 through whichthe central portion Wc is suctioned, and the suction line 411communicates with a central suction mechanism 412 such as, but notlimited to, a vacuum pump. The suction line 411 is provided with acentral pressure sensor 413 configured to measure a suction pressure.Although the central pressure sensor 413 is not particularly limited, adiaphragm pressure gauge may be used, for example.

The peripheral holder 420 is connected to a suction line 421 throughwhich the peripheral portion We is suctioned, and the suction line 421communicates with a suction mechanism 422 such as, but not limited to, avacuum pump. The suction line 421 is provided with a peripheral pressuresensor 423 configured to measure a suction pressure. Although theperipheral pressure sensor 423 is not particularly limited, a diaphragmpressure gauge may be used.

Further, as illustrated in FIG. 31, a recess 400 a which is recessedhigher than the central holder 410 is formed at a portion of a peripheryof the attraction plate 400 where the peripheral holder 420 is provided.As will be described later, the peripheral portion We is removed bybeing lifted up by periphery removers 440. The recess 400 a provides aspace into which the peripheral portion We is raised.

With this configuration, the central holder 410 and the peripheralholder 420 are capable of suctioning and holding the central portion Wcand the peripheral portion We individually. Further, the centralpressure sensor 413 and the peripheral pressure sensor 423 are capableof measuring a suction force for the central portion Wc and a suctionforce for the peripheral portion We, respectively.

A rotating mechanism 430 configured to rotate the attraction plate 400around a vertical axis is provided on a top surface of the attractionplate 400. The rotating mechanism 430 is supported at a supportingmember 431. Further, the supporting member 431 (rotating mechanism 430)is supported at the arm member 72.

At a lateral side of the attraction plate 400, the periphery removers440 are provided along a circumferential direction of the attractionplate 400. Each periphery remover 440 includes a wedge roller 441 and asupport roller 442.

The wedge roller 441 has a wedge shape with a pointed leading end, whenviewed from the side. The wedge roller 441 is inserted into an interfacebetween the processing target wafer W and the support wafer S from theedges thereof. The peripheral portion We is lifted up by the insertedwedge roller 441 to be separated and removed from the processing targetwafer W.

The support roller 442 penetrates a center of the wedge roller 441 andsupports the wedge roller 441. The support roller 442 is configured tobe moved in a horizontal direction by a moving mechanism (not shown). Asthe support roller 442 is moved, the wedge roller 441 is also moved.Further, the support roller 442 is configured to be rotated around avertical axis. As the support roller 442 is rotated, the wedge roller441 is also rotated. Further, in the present exemplary embodiment, aso-called free roller which is rotated by the rotation of the chuck 100as will be described later is used as the support roller 442. However,the support roller 442 may be rotated actively by a rotation mechanism(not shown).

A rotation shaft 443 is provided on a top surface of the support roller442, and the rotation shaft 443 is supported by a moving mechanism 444.The moving mechanism 444 is provided at a peripheral portion of a topsurface of the supporting member 431. The moving mechanism 444 is, forexample, an air cylinder, and is capable of moving the wedge roller 441and the support roller 442 in the horizontal direction via the rotationshaft 443.

In the wafer processing according to the third exemplary embodiment, thecombined wafer T as shown in FIG. 29A is transferred into the modifyingapparatus 60. In the modifying apparatus 60, a peripheral modificationlayer M11 and a split modification layer M21 are formed in theprocessing target wafer W in sequence, as illustrated in FIG. 29B(processes C1 and C2 in FIG. 28). Further, the way how to form theperipheral modification layer M10 in the process Cl is the same as theprocess Al, and the way how to form the split modification layer M21 inthe process C2 is the same as the process A2.

Subsequently, the transfer arm 71 of the wafer transfer device 70advances into the modifying apparatus 60, and the peripheral portion Weis removed (process C3 of FIG. 28), as depicted in FIG. 29C.

In the process C3, the rear surface Wb of the processing target wafer Wis first attracted to and held by the attraction plate 400 of thetransfer arm 71. Then, as shown in FIG. 32A, the wedge roller 441 ismoved to the combined wafer T and brought into contact with theinterface between the processing target wafer W and the support wafer S.At this time, by rotating the attraction plate 400, the wedge roller 441is rotated in the reverse direction, when viewed from the top. Then, asdepicted in FIG. 32B, while rotating the attraction plate 400, the wedgeroller 441 is further moved to be inserted into the interface betweenthe processing target wafer W and the support wafer S. As a result, theperipheral portion We is lifted up to be separated from the processingtarget wafer W, and attracted to and held by the peripheral holder 420.

Thereafter, while attracting and holding the peripheral portion We withthe peripheral holder 420, the transfer arm 71 is retreated from themodifying apparatus 60 in the state that the peripheral portion We isheld by the plurality of wedge rollers 441. Then, the peripheral portionWe is collected by a collector (not shown) which is provided at anoutside of the modifying apparatus 60.

Furthermore, when removing the peripheral portion We, the pressure bywhich the central portion Wc is suctioned and the pressure by which theperipheral portion We is suctioned are measured by the central pressuresensor 413 and the peripheral pressure sensor 423, respectively. If theperipheral portion We is appropriately removed, the pressure for thecentral portion Wc becomes zero, and the pressure for the peripheralportion We becomes a preset pressure. Meanwhile, if the peripheralportion We is not removed properly, the pressure for the peripheralportion We, for example, becomes zero. In this way, by measuring thesuction pressures with the central pressure sensor 413 and theperipheral pressure sensor 423, presence/absence of the peripheralportion We upon the processing target wafer W can be detected, and itcan be checked whether the peripheral portion We is removed from theprocessing target wafer W.

Afterwards, in the modifying apparatus 60, an internal modificationlayer M31 is formed (process C4 of FIG. 28), as illustrated in FIG. 29D.Further, the way how to form the internal modification layer M31 in theprocess C4 is the same as the process A3.

Next, the combined wafer T is transferred into the processing apparatus80 by the wafer transfer device 70. First, in the processing apparatus80, when the combined wafer T is delivered onto the chuck 81 from thetransfer arm 71, the rear surface Wb side of the processing target waferW (hereinafter, referred to as “rear surface wafer Wb3”) is separatedstarting from the internal modification layer M31 (process C5 of FIG.28), as shown in FIG. 29E. Further, the method of separating theprocessing target wafer W in the process C5 is the same as the processA5. Further, the way how to separate the processing target wafer W isnot limited to the method of using the transfer arm 71. By way ofexample, it may be carried out by using the same apparatus as theperiphery removing apparatus 61 shown in FIG. 20.

Thereafter, the rear surface Wb of the processing target wafer W isground (process C6 of FIG. 28), as shown in FIG. 29F, and cleaning ofthe rear surface Wb in the cleaning apparatus 41 (process C7 of FIG. 28)and wet-etching of the rear surface Wb in the etching apparatus 40(process C8 of FIG. 28) are performed in sequence. Then, the waferprocessing in the wafer processing system 1 including the aforementionedseries of processes is completed.

In the present exemplary embodiment as well, since the peripheralmodification layer M1 and the internal modification layer M3 are formedwithin the processing target wafer W in this sequence, the same effectas obtained in the first exemplary embodiment can be achieved. Besides,since the formation of the peripheral modification layer M11 in theprocess C1, the removal of the peripheral portion We in the process C3and the formation of the internal modification layer M31 in the processC4 are performed in the single modifying apparatus 60, the throughput ofthe wafer processing can be maintained high. Furthermore, in the presentexemplary embodiment, although the peripheral portion We is removedwithin the modifying apparatus 60 in the process C3, a separateapparatus may be used.

Now, another exemplary embodiment of the modifying apparatus 60 will beexplained. The modifying apparatus 60 according to the above-describedexemplary embodiment has the single laser head 110. As shown in FIG. 33,however, a plurality of, for example, two laser heads 110 and 500 may beprovided. In the present exemplary embodiment, the laser head 110 isreferred to as first laser head 110, and the laser head 500 is referredto as second laser head 500, for the convenience of explanation.Further, the number of the laser heads is not limited to the example ofthe present exemplary embodiment. In FIG. 33, for the sake of simpleillustration, the macro-camera 140 and the micro-camera 150 are omitted.

The second laser head 500 is provided at a positive Y-axis side of thefirst laser head 110. The second laser head 500 has the sameconfiguration as the first laser head 110. That is, the second laserhead 500 has a lens 501 and a LCOS (not shown).

A support structure for the second laser head 500 is the same as thesupport structure for the first laser head 110. That is, the secondlaser head 500 is supported at a supporting member 510, a rail 511, anelevating mechanism 520 and a moving mechanism 521. The second laserhead 500 is configured to be movable up and down and, also, movable inthe Y-axis direction.

In this configuration, when forming the internal modification layer M1in the first exemplary embodiment, for example, the first laser head 110and the second laser head 500 are arranged on the same circle at aperipheral portion of the processing target wafer W, as illustrated inFIG. 34. Then, while rotating the processing target wafer W, laser lightL12 is radiated from the first laser head 110, and laser light L13 isradiated from the second laser head 500. As a result, a peripheralmodification layer M12 is formed by the laser light L12, and aperipheral modification layer M13 is formed by the laser light L13. Eachof the peripheral modification layers M12 and M13 is formed half-round,and these peripheral modification layers M12 and M13 form thering-shaped peripheral modification layer M1 together. That is, in thepresent exemplary embodiment, the processing target wafer W only needsto be rotated by 180 degrees when forming the peripheral modificationlayer M1. Accordingly, a time required to form the peripheralmodification layer M1 can be shortened, so that the throughput of thewafer processing can be further improved.

Further, in the above-described exemplary embodiment, the laser lightL12 from the first laser head 110 and the laser light L13 from thesecond laser head 500 are radiated to the same depth within theprocessing target wafer W, so the peripheral modification layer M12 andthe peripheral modification layer M13 are formed at the same depth.However, by radiating the laser light L12 and the laser light L13 todifferent depths, the peripheral modification layer M12 and theperipheral modification layer M13 may be formed at the different depths.

Moreover, when forming the internal modification layer M3, the firstlaser head 110 and the second laser head 500 are arranged on the samecircle at the peripheral portion of the processing target wafer W, asshown in FIG. 35. Then, while rotating the processing target wafer W,the first laser head 110 and the second laser head 500 are respectivelymoved in the Y-axis directions from the peripheral portion of theprocessing target wafer W toward the central portion thereof. That is,the first laser head 110 is moved in the positive Y-axis direction,whereas the second laser head 500 is moved in the negative Y-axisdirection. During the rotating of the processing target wafer W and themoving of the laser heads 110 and 500, laser light L32 is radiated tothe inside of the processing target wafer W from the first laser head110, and laser light L33 is radiated to the inside of the processingtarget wafer W from the second laser head 500. As a result, an internalmodification layer M32 is formed by the laser light L32, and an internalmodification layer M33 is formed by the laser light L33. Each of theinternal modification layers M32 and M33 is formed in a spiral shape, sothat the internal modification layer M3 is formed within the entiresurface of the processing target wafer W. Since the internalmodification layers M32 and M33 are formed at the same time as statedabove, the time taken to form the internal modification layer M3 can beshortened, so that the throughput of the wafer processing can be furtherimproved.

In the above-described exemplary embodiments, the split modificationlayer M2 is formed in the modifying apparatus 60 by using the laser head110 which is used to form the peripheral modification layer M1 and theinternal modification layer M3. However, another laser head (not shown)may be used. Further, in the modifying apparatus 60, the peripheralmodification layer Ml, the split modification layer M2 and the internalmodification layer M3 may be formed by using all different laser heads(not shown).

By way of example, in the above-described exemplary embodiments, thenon-bonding region Ab is formed at an interface between the processingtarget wafer W and the support wafer S before being bonded. However, thenon-bonding region Ab may be formed after they are bonded. By way ofexample, by radiating laser light to a peripheral portion of the oxidefilm F after the processing target wafer W and the support wafer S arebonded, a bonding strength therebetween can be reduced, so that thenon-bonding region Ab can be formed.

It should be noted that the exemplary embodiment is illustrative in allaspects and is not anyway limiting. The above-described exemplaryembodiment may be omitted, replaced and modified in various ways withoutdeparting from the scope and the spirit of claims.

EXPLANATION OF REFERENCE NUMERALS

1: Wafer processing system

60: Modifying apparatus

100: Chuck

110: Laser head

S: Support wafer

T: Combined wafer

W: Processing target wafer

1. A substrate processing apparatus configured to process a substrate,comprising: a substrate holder configured to hold, in a combinedsubstrate in which a front surface of a first substrate and a frontsurface of a second substrate are bonded to each other, the secondsubstrate; a periphery modification unit configured to form a peripheralmodification layer by radiating laser light for periphery to an insideof the first substrate held by the substrate holder along a boundarybetween a peripheral portion of the first substrate as a removing targetand a central portion thereof; and an internal modification unitconfigured to form, after the peripheral modification layer is formed bythe periphery modification unit, an internal modification layer byradiating laser light for internal surface to the inside of the firstsubstrate held by the substrate holder along a plane direction of thefirst substrate.
 2. The substrate processing apparatus of claim 1,further comprising: a periphery removing unit configured to remove theperipheral portion of the first substrate starting from the peripheralmodification layer after the internal modification layer is formed bythe internal modification unit; and a substrate separating unitconfigured to separate the first substrate starting from the internalmodification layer after the peripheral portion is removed by theperiphery removing unit.
 3. The substrate processing apparatus of claim2, further comprising: a processing unit configured to grind a rearsurface of the first substrate bonded to the second substrate after thefirst substrate is separated by the substrate separating unit, whereinthe substrate separating unit serves as a transfer unit configured totransfer the combined substrate between the substrate holder and theprocessing unit.
 4. The substrate processing apparatus of claim 2,further comprising: an additional substrate holder configured to holdthe second substrate in the combined substrate, wherein the peripheryremoving unit removes the peripheral portion of the first substrate heldby the additional substrate holder, and the substrate separating unitseparates the first substrate held by the additional substrate holder.5. The substrate processing apparatus of claim 1, further comprising: aremoving/separating unit configured to perform, after the internalmodification layer is formed by the internal modification unit, removingof the peripheral portion of the first substrate starting from theperipheral modification layer and separating of the first substratestarting from the internal modification layer at a same time.
 6. Thesubstrate processing apparatus of claim 5, further comprising: aprocessing unit configured to grind a rear surface of the firstsubstrate bonded to the second substrate after the first substrate isseparated by the removing/separating unit, wherein theremoving/separating unit serves as a transfer unit configured totransfer the combined substrate between the substrate holder and theprocessing unit.
 7. The substrate processing apparatus of claim 5,further comprising: an additional substrate holder configured to holdthe second substrate in the combined substrate, wherein theremoving/separating unit performs the removing of the peripheral portionand the separating of the first substrate at the same time on the firstsubstrate held by the additional substrate holder.
 8. The substrateprocessing apparatus of claim 2, further comprising: a periphery holderconfigured to hold the peripheral portion when the internal modificationlayer is formed by the internal modification unit.
 9. The substrateprocessing apparatus of claim 1, wherein the periphery modification unitforms the peripheral modification layer such that a crack, whichdevelops from the peripheral modification layer in a thickness directionof the first substrate, reaches the front surface of the firstsubstrate.
 10. The substrate processing apparatus of claim 1, furthercomprising: a periphery removing unit configured to remove theperipheral portion of the first substrate starting from the peripheralmodification layer after the peripheral modification layer is formed bythe periphery modification unit and before the internal modificationlayer is formed by the internal modification unit; and a substrateseparating unit configured to separate the first substrate starting fromthe internal modification layer after the internal modification layer isformed by the internal modification unit.
 11. The substrate processingapparatus of claim 10, wherein the periphery removing unit serves as atransfer unit configured to transfer the combined substrate to thesubstrate holder.
 12. The substrate processing apparatus of claim 1,wherein a laser head is shared by the periphery modification unit andthe internal modification unit, and the laser head switches the laserlight for periphery and the laser light for internal surface.
 13. Thesubstrate processing apparatus of claim 12, wherein the laser headincludes multiple laser heads.
 14. The substrate processing apparatus ofclaim 12, wherein the laser head is configured to be moved up and downin a vertical direction and, also, moved in a horizontal direction. 15.A substrate processing method of processing a substrate, comprising:holding, in a combined substrate in which a first substrate and a secondsubstrate are bonded to each other, the second substrate with asubstrate holder; forming a peripheral modification layer by radiatinglaser light for periphery from a periphery modification unit to aninside of the first substrate held by the substrate holder along aboundary between a peripheral portion of the first substrate as aremoving target and a central portion thereof; and forming, after theforming of the peripheral modification layer by the peripherymodification unit, an internal modification layer by radiating laserlight for internal surface from an internal modification unit to theinside of the first substrate held by the substrate holder along a planedirection of the first substrate.
 16. The substrate processing method ofclaim 15, further comprising: removing, after the forming of theinternal modification layer by the internal modification unit, theperipheral portion of the first substrate starting from the peripheralmodification layer by a periphery removing unit; and separating, afterthe removing of the peripheral portion by the periphery removing unit,the first substrate starting from the internal modification layer by asubstrate separating unit.
 17. The substrate processing method of claim15, wherein after the forming of the internal modification layer by theinternal modification unit, removing of the peripheral portion of thefirst substrate starting from the peripheral modification layer andseparating of the first substrate starting from the internalmodification layer are performed at a same time by using aremoving/separating unit.
 18. The substrate processing method of claim15, further comprising: removing, with a periphery removing unit, theperipheral portion of the first substrate starting from the peripheralmodification layer after the forming of the peripheral modificationlayer by the periphery modification unit and before the forming of theinternal modification layer by the internal modification unit; andseparating, with a substrate separating unit, the first substratestarting from the internal modification layer after the forming of theinternal modification layer by the internal modification unit.